Continuous method and apparatus for manufacturing articles from foamed thermoplastic material



Nov. 25, 1969 T. W. WINSTEAD CONTINUOUS METHOD AND APPARATUS FORMANUFACTURING .ARTICLES FROM FOAMED THERMOPLASTIC MATERIAL Filed Aug.19, 1965 12 Sheets-Sheet v l IIILIIHJI Hllll Salvage INVENTOR THOMAS w.WlNSTEAD ATTORNEY Nov. 25, 1969 T. w. WINSTEAD 3,479,694 CONTINUOUSMETHOD AND APPARATUS FOR MANUFACTURING 7 ARTICLES FROM FOAMEDTHERMOPLASTIC MATERIAL Filed Aug. 19, 1965 12 Sheets-Sheet 2 III 1 IINVENTOR THOMAS W. WINSTEAD FIGZZ ATTORNEY Nov. 25, 1969 'r. w. WINSTEAD3,479,694

CONTINUOUS METHOD AND APPARATUS FOR MANUFACTURING ARTICLES FROM FOAMEDTHERMOPLASTIC MATERIAL Filed Aug. 19, 1965 l2. Sheets-Sheet 3 THOMAS W.WINSTEAD BY lwmw- ATTORNEY T. W. WINSTEAD CONTINUOUS METHOD ANDAPPARATUS FOR MANUFACTURING ARTICLES FROM FOAMED THERMOPLASTIC MATERIALFiled Aug. 19, 1965 INVENTOR THOMAS w. WINSTEAD ATTORNEY Nov. 25, 1969T. WINSTEAD 3,479,694

CONT 0U OD AP ATUS FOR NUFACTURING A CL M FOAMED RMOPLAST MATERIAL FiledAug. 19, 1955 12 Sheets-Sheet INVENTOR THOMAS W. WINSTEAD BY am ATTORNEYNov. 25, 1969 'r. w. WINSTEAD 3,479,694

CONTINUOUS METHOD AND APPARATUS FOR MANUFACTURING ARTICLES FROM FOAMEDTHERMQPLASTIC MATERIAL Filed Aug. 19, 1955 12 Sheets-Sheet 6 INVENTORTHOMAS W. WINSTEAD BY @MM ATTORNEY Nov. 25, 1969 'r. w. WINSTEAD3,479,694

CONTINUOUS METHOD AND APPARATUS FOR MANUFACTURING ARTICLES FROM FOAMEDTHERMOPLASTIC MATERIAL Filed Aug. 19, 1965 12 Sheets-Sheet '7 1 i I l Z4 l 1 E g r I I sea I 1 I I00 H{L.+-|oz w FHL,

INVENTOR THOMAS W. WINSTEAD BY QMM ATTORNEY 3,479,694 RING Nov. 25, 1969T. w. WINSTEAD CONTINUOUS METHOD AND APPARATUS FOR MANUFACTU ARTICLESFROM FOAMED THERMOPLASTIC MATERIAL l2 Sheets-Sheet 8 Filed Aug 19, 1965F l6. l3

ENVENTOR ATTORNEY 3,479,694 RING AL Nov. 25, 1969 T. w. WINSTEADCONTINUOUS METHOD AND APPARATUS FOR MANUFACTU ARTICLES FROM FOAMEDTHERMOPLASTIC MATERI Filed Aug. 19, 1965 12 Sheets-Sheet 9 ATTORNEY Nov.25, 1969 1'. w. WINSTEAD' 3,479,694

CONTINUOUS METHOD AND APPARATUS FOR MANUFACTURING ARTICLES FROM FOAMEDTHERMOPLASTIC MATERIAL Filed Aug. 19, 1965 1,2 Sheets-Sheet 10 INVENTORTHOMAS w. WI'NSTEAD F/G. 15

BY 0 mm ATTORNEY Nov. 25, 1969 T. w. WINSTEAD 3,479,694

CONTINUOUS METHOD AND APPARATUS FOR MANUFACTURING ARTICLES FROM FOAMEDTHERMOPLASTIC MATERIAL Filed Aug. 19, 1965 12 Sheets-Sheet 11 EB I m o EI y 52 8 E 1 t k 05 o 13 ll N N 2 l 5 SI, g m 2 I] Q m I 09 0 o II 5 i H2 3 I] g II II C, M D I H (o I }1:::: I O I Q I R 'l F El INVENTORTHOMAS W. WINSTEAD BY WM- ATTORNEY Nov. 25, 1969 1-. w. WINSTEAD3,479,694

commuous METHOD AND APPARATUS FOR MANUFACTURING ARTICLES FROM FOAMEDTHERMOPLASTIC MATERIAL Filed Aug. 19, 1965 12. Sheets-Sheet l2 p a w a 3E M g o E (O O O k H] N A. L 3 o m o 2 2 n Q g. o

IN-VENTOR THOMAS W. WINSTEAD BY QMJWW ATTORNEY United States Patent M3,479,694 CONTINUOUS METHOD AND APPARATUS FOR MANUFACTURING ARTICLESFROM FOAMED THERMOPLASTIC MATERIAL Thomas W. Winstead, Baltimore, Md.(Williamson Lane, Cockeysville, Md. 21030) Filed Aug. 19, 1965, Ser. No.480,917 Int. Cl. B29c 17/00, 17/14 U.S. Cl. 18-19 Claims ABSTRACT OF THEDISCLOSURE This invention relates to a method and apparatus for formingand cutting plastic articles, and consists more particularly in acontinuous, integrated system for the manufacture of formed articlesfrom foamed or cellular thermoplastics.

Conventionally, in making formed articles from foamed thermoplastics, amultiple stage method and apparatus have been employed. First, foamedsheeting has been extruded and collected on rolls which have been storeduntil ready for use in a sheet-forming machine which reheats thematerial on a progressive basis and forms it into molds by the use ofdifferential air pressure, plungers, or both. After forming, the web istransferred to a cutting machine which severs the formed articles fromthe selvage. In other words, the extrusion operation, the formingoperation, and the cutting operation require entirely separate steps andmachinery, and although this system has been satisfactory in certainrespects, it has many limitations affecting cost, quality control andoperational control.

For example, with the conventional multiple stage operation, thefollowing disadvantages and limitations are noted:

(l) Considerably more floor space is required for the multiple steps andmachinery than is required for an integrated system.

(2) Because of the usual blown bubble method used in producing thesheet, it is very difficult to produce low density material of goodquality, and this naturally affects cost.

(3) Because of the separation of the extrusion and fabricatingoperations, quality control becomes more difiicult and costly; aconsiderable amount of sheeting may be made for subsequent forming withdefects which are not detected until the forming operation is begun, atwhich time it is too late to take corrective measures. This naturallyresults in the rejection of large quantities of material. 1

(4) Since foam sheeting has excellent thermal insulating properties, itis difiicult and costly from an energy standpoint to heat it properlyand uniformly during the fabrication step.

(5) With certain types of thermoplastic foam sheeting, there is a periodof aging during which volatiles used in the foaming process are evolvedand replaced by air. Therefore, careful attention must be paid to thetime when the re-heating takes place during the fabricating step, be-

Patented Nov. 25, 1969 ICC cause the residual content of the volatilecan have an appreciable effect on the final density of the product,necessitating operational controls which further complicate the process.

(6) Because of the difficulties in obtaining uniform heat and because ofthe necessity of waiting until a large percentage of the volatiles haveevolved from the material, it is not possible to form such foamedsheeting as readily or as deeply as would otherwise be the case.

(7) A multiple stage process is always more difficult toautomate andnecessarily requires more manpower than for an integrated process, whichagain affects costs adversely.

It is therefore the primary object of the present invention to providean integrated system for continuously extruding, forming and cuttingplastic articles of foamed or cellular material and to thereby overcomethe disadvantages and limitations inherent in conventional methods.

Another object is to provide a method and apparatus of this naturewherein the individual steps and apparatus involved in the integratedsystem are coordinated for the proper sequential operation, both withrespect to time and the geometry of the system to produce foamed plasticarticles of high quality.

With the above and other objects in view which will appear as thedescription proceeds, the invention consists in the novel featuresherein set forth, illustrated in the accompanying drawings, and moreparticularly pointed out in the appended claims.

Referring to the drawings in which numerals of like character designatesimilar parts throughout the several views:

FIG. 1 is a schematic view illustrating the integrated system of theinvention;

FIG. 2 is an elevational view partially in section illustrating theforming wheel unit;

FIG. 3 is a plan view partially in section taken at right angles to theillustration in FIG. 2;

FIG. 4 is an enlarged side elevation of the forming wheel;

FIG. 5 is a sectional view taken on line 55 of FIG. 4, illustrating themold structure;

FIG. 6 is a further enlarged plan view of a mold;

FIG. 7 is a sectional view taken on line 77 of FIG. 6;

FIG. 8 is a similar view taken on line 88 of FIG. 6;

FIG. 9 is a plan view of the vacuum control manifold valve plate;

FIG. 10 is a sectional view taken on line 10-10 of FIG. 9;

FIG. 11 is a sectional view taken on line 1111 of FIG. 9;

FIG. 12 is a top plan view of the article cutting unit;

FIG. 13 is a sectional view taken on line 1313 of FIG. 12;

FIG. 14 is a sectional view taken on line 14-14 of FIG. 13;

FIG. 15 is a sectional view taken on line 15-15 of FIG. 12;

FIG. 16 is a feeding end elevation of the packaging unit;

FIG. 17 is a view of the same in side elevation; and

FIG. 18 is the delivery end elevation.

Referring first to FIG. 1, the integrated system includes an extrusiondevice generally indicated at 20, which is preferably, but notnecessarily, of the type shown and described in my copending applicationSer. No. 475,734, filed July 29, 1965. Here, an expandible thermoplasticmaterial incorporating suitable blowing agents is extruded through adie, forming a continuous thermoplastic strip or sheet 22. The sheet 22travels over a spreading yoke 23,

also shown in my said copending application, from which it is conductedaround the periphery of'a forming whe'el' 24 which vacuum forms thearticles on the sheet 22.

By sequential valving, to be described, the vacuum is applied to thesuccessive molds on the forming wheel 24 as the sheet 22 is tangent tothe respective fiat faces of the forming wheel and after the sheet hasbeen flattened and stretched by the spreading yoke 23. I

The formed articles, while still carried by the sheet 22, are thenstripped tangentially from the upper side of the forming wheel and thesheet and articles are conducted to the cutting unit 25 where the formedarticles are removed from the sheet and directed to a stacking unit 26.The remaining selvage 22a is thereupon conducted to a granulatingmachine 27 which automatically divides it into fine particles, afterwhich it -is fed back into the extrusion equipment.

In order to facilitate the sequential operation of the integrated unitsof the system and to insure proper spacing of said units, the formingwheel unit 24, the cutting unit 25 and the stacking unit 26 are mountedon suitable wheels or rollers 28, 29 and 30 respectively which may runon tracks, as shown. It should also be pointed out that as distinguishedfrom some of the conventional extruding and forming systems, whereinarelatively wide sheet of plastic'is extruded so" as to provide a webwidth which will accommodate a large number'of cavities when formed, thepresent invention contemplates the extrusion of narrow strips. Thedifficulties of removing corrugations from an extruded wide flat sheetof expandible thermoplastic material after emergence from the die arealmost insurmountable in very low density foams, such, for example, asthose under 3 lbsiper cubic foot. Also, the slow linear speed generallyassociated with wide webs inherently includes a time element which isparticularly detrimental to subsequent forming of foam materials fromsheet. Because of the cooling effect upon expansion desirable to formthe material within the shortest possible interval of time. A narrow webof the order of 12" or less in width reduces this time increment andalso minimizes heat loss from the material, which obviously seriouslyaffects formability. Since both quality and immediately after'emergencefrom thejdie orifice, it is actually be determined maximum practicalwidths which,

if exceeded, will preclude quality forming of articles, assuming allother variables remain constant. In certain extrudable foams, such asstyrene, frequently volatile blowing agents are used which have acertain plasticizing effect on. the polymer. Since a high percentage ofsuch ingredients are evolved, again within a short time interval afterleaving the die orifice, it is only byextruding narrow strips atextremely high linear rates that the beneficial plasticizingeffects canbe attained during the forming step. This narrow strip concept and highlinear rate with respect to time offers a method which'is not possibleby other means The narrow strip concept minimizes the problem ofcorrugations and spreading of the material as it expands afteremergengence from the die orifice; it

ing low density, deep drawn articles of high quality at I low cost.

As seenin FIGS, 25, the forming wheel 24 comprises a series of flat,peripherally mounted molds 31, which,

in the embodiment illustrated, jointly form a wheel of octagonalperiphery. These molds are supported on a wheel disc 32 by suitablescrew-threaded fixtures. 33

(FIGS. 4 and 5) engaging cross bars 33a, fixed to the outer edge of disc32. By means of'these fixtures, the'in'- dividual molds may also beradially adjusted on the disc for proper positioning relative to oneanother. The disc 32 is keyed to a rotatable shaft 34 so as to rotatetherewith and is held in place on the shaft by a bolt 35 and plate 36.

The shaft 34 is mounted in cantilever (FIG. 3) and rotatably supportedby bearings 37 and is driven by a sprocket 38 and chain 39 from a drivesprocket (not shown) mounted on a motor drive unit 40. This motor driveunit is a variable speed unit of conventional type with suitable controlfor varying the speed of the forming wheel 24.

The vacuum forming system for the wheel 24 comprises a vacuum pump 41which creates suction in the connecting pipe or hose 42, connected tothe manifold plate 43, shown in detail in FIGS. 9 and 10 and hereinafterreferred to. As seen in FIG. 5, the manifold plate 43 is held inintimate contact with the hub 44 of the forming wheel 24 by a spring 45interposed between the inner bearing 37 and the outer face of themanifold plate and forces the latter against the forming wheel hub 44.

The manifold plate "43 is, of course, held stationary by tube 42 whilethe hub 44 rotates with the shaft 34. As seen in FIG. 9, the manifoldplate 43 is provided with a relatively long, arcuate slot 46, one end ofwhich communicates with the suction pipe 42 as at 47. As shown in FIGS.4 and 5, each of the vacuum molds 31 on the periphery' of the wheel 24is connected by a pipe 48 to a corresponding port 49 in the hub 44.Thus, as the hub rotates, each port 49 sequentially comes to a positionon the manifold plate where the arcuate slot 46 begins to cover theport, thus creating a vacuum within the mold cavity. As the hub andwheel continue to rotate, the slot 46 maintains the vacuum with a numberof successive molds on the wheel over a large percentage of a fullrevolution, and when the end of the slot is reached, the vacuum is cutoff.

Preferably, a valve 50 leading to one end of the slot 46 is employed topermit the maintenance of a good vacuum on start-up. This valveis-maintained in closed position until sufficient vacuum has beenestablished, whereupon it is opened as initial vacuum is established inall of the molds communicating with the slot 46.

A second, shorter arcuate slot 51 is connected to an air source at 52which, in proper sequence, communicates with each mold cavity andthereby ejects the finished product from the cavity, as will laterappear.

The molds 31 are identical, and a description of one will sufiice forall. As seen in FIGS. 5-8, each mold is provided with a suitably shapedmold cavity 53 communicating through appropriately spaced vacuum ports'54 with a vacuum chamber 55 formed in the body'of the mold.

As best seen in FIG. 6, the vacuum chamber 55 is in the form of anendless channel extending around the bottom wall of the mold andconnected crosswise by a central channel 55a, thus equally distributingthe vacuum created inthe chamber. The cross channel 55a is provided witha threaded insert 56 by means of which it is operatively connected to acoupling 57 carried on the end of the respective vacuum hose 48.Preferably, the insert 56 is cast in the mold during its forming.

In order to hold and seal the thermoplastic sheet around the entireperiphery of the cavity'53 during the forming operation, a vacuum groove58 is provided in the top surface of the upper edge-of the moldwalLThis-channel communicates withthe vacuum chamber 55 by a-passage--way 59. This, sealing'operation may be effectedprior to or simultaneouswith the application of vacuum to the main mold cavity 53 by meansofthevacuum pump 41 so that the vacuum groove is first evacuatedand'clamps the edges of the sheet completely around the cavity, holding.them firmly during the subsequent drawing of material into the cavityitself. The sequencing of. these two stepsmay be accomplished in one ofseveral ways. It is most easily accomplished by relatively restrictingflow from the cavity while maximizing flowfrom the vacuum groove '58itself. This precludes the need for complicated channeling and valving.However, the clamping groove and the cavity may actually be segregatedfrom one another and separately valved in sequence. It may also. benoted that the vacuum groove 58 may be a continuous groove or it maycomprise a series of suitably spaced vacuum grooves extending around theupper edge of the mold 31.

.. As previously indicated, the manifold plate 43. is provided with ashort arcuate slot 51 connected to an air source at 52. This slot 51communicates with each mold cavity through vacuum chamber 55 in propersequence as the hub 44 rotates relative to the manifold plate andthereby ejects the finished product from the cavity at the proper time.

The complete cycle of the forming operation is best illustrated in FIGS.1 and 2 where it will be seen that the sheet of foamed thermoplastic 22is extruded from the die 20, in the manner described in my saidcopending application, and after expanding passes over the spreadingyoke 23, from which it is directed downwardly, and tangentially engagesthe mold 31a across its cavity opening as the wheel 24 rotates. Here itis immediately sealed around the edges of the cavity by the vacuumgroove 58.

At this point, vacuum has been admitted to the arcuate slot 46 in themanifold plate 43 which continuously applies vacuum to the mold cavitiesas they sequentially come into registry with the arcuate slot. By thetime the mold 310! has reached the point 31b at the upper end of thewheel, the vacuum has been cut off from the mold cavity and air pressureis applied from slot 51 to eject the formed article from the moldcavity.

The continuous web 22 with the formed articles 22b still engaged istangentially stripped from the forming wheel and guided by a pair ofspaced edge-engaging rollers 60 and a backing roller 61 to the cuttingoperation to be later described. In instances where the foamed sheet 22is relatively stiff or thick, it is preferable to employ a crimpingroller 62. This crimping roller is positioned transversely of theperiphery of the forming wheel 24 and spaced upwardly therefrom so thatit only engages the sheet 22 at the junctions of the respective flatmolds 31. This is accomplished at the top of the wheel just as the'material leaves the mold 31b and provides a hinge point across thestrip which precludes deformation of the articles 22b or the edgesaround the articles as the web is pulled straight and tangentially fromthe wheel. As before indicated, some thermoplastic forms require thistreatment, while others do not While the illustrated embodiment of theinvention employs a solid shaft 34, this shaft may be hollow in orderthat water may be brought to the mold wheel through the appropriaterotary joints and then to the individual molds whenever water cooling isrequired. When foamed materials are being produced, water cooling is notparticularly useful because of the poor heat transfer characteristics oflow density foams and poor .conductivity of such materials to the watercooled molds. Therefore, the present invention contemplates the use ofair cooling by means of an air blower 63 which directs air as at 64 tothe lower portion of the wheel periphery, and, if desired, it may besuitably conducted to a point adjacent the upper portion of the wheel,as at 65.

Referring now to the cutting unit 25, shown in FIGS. 12 to 15, ahorizontally disposed cutting roll 66 is rotatably supported at oppositeends by bearings 67 carried at the upper extremities of a pair ofplunger rods 68 extending from air actuated plungers in cylinders 69.Thus, as will later appear, cutting pressure may be varied by increasingor decreasing the air pressure operating the cylinders 69. As best seenin FIGS. 12 and 14, the cutting roll 66 is provided with two radiallyopposed cavities 70 which are bounded by raised cutting knives 71. Thecavities and cutting knives are contoured to conform to the contours ofthe articles which have been formed in the thermoplastic sheet 22 sothat as the sheet advances between the cutting roll 66 and a backup oranvil roll 72 journalled in bearings 73, the knives71 sever the formedarticles from the selvage with the exact profile defined by the molds.As hereinafter explained, the rotation of the cutting roll 66 and therelative peripheral locationsof the two sets of cutting knives arecoordinated with the rota} tion of the forming wheel 24 so as to insureprecise registry. of the formed articles in the advancing sheet22 withthe cutting knives. I

The cylinders 69 are supported at their lower ends by pivotalconnections 74, whereby the entire cutter roll assembly may be swungforward for rapid change of cutter roll sizes. To facilitate thisoperation, the bearings 67 are supported. for vertical slidingmovement-by a pair of guide rails 75 and 76, as seen in FIG. 13. Theforward guide rail '75 is shorter than the rear guide rail 76 so thatwhen the pistons on rods 68 are drawn to the bottoms of the cylinders69, the bearings 67 and the cutting roll 66 supported thereby can clearthe guideways at the bottom of the short guideway 75 when the assemblyis swung outwardly. The drive means for the cutting assembly comprises amitered gear box- 77 which, as seen in FIGS. 13 and l4,v is driven bythe forming wheel motor 40 through a universal telescoping shaft 78. Asprocket 79, driven by the gear box 77, rotates a sprocket 80 throughsprocket chain or belt 81. The sprocket 80 is mounted at the inner endof a shaft 82, journalled in bearings 83, said shaft 82 carrying asecond sprocket 84 at its outer end which is operatively connected to asprocket 85 by a chain 86. This latter sprocket 85 drives splined shaft87 which, in turn, drives an internal shaft 88 connected to a coupling89. The coupling and internal shaft 88 may be movedin and out ofengagement with the cutter roll 66 by means 'of the lever 90 which isactuated by an air cylinder 91.

The entire assembly just described is mounted on a bracket 92 which maybe moved vertically up or down by the handle and threaded stud 93,thereby bringing the position of the coupling 89 into line with thecenter of the shaft of the cutter roll 66. This permits accommodation ofvarious sizes of cutter rolls, all of which may be driven even thoughtheir vertical center line may be at different positions. The chain 81which connects sprocket 79 to sprocket 80 may be kept in tension by anidler 94 (FIG. 15).

As previously pointed out, the forming unit 24 and the cutting unit 25are mounted on rollers 28 and 29 respectively, and by employing atelescoping shaft at 78, these units can be moved toward or away fromone another, depending upon the timing desired.

In order to link the forming unit 24 and the cutting unit 25 togetherand maintain the proper spacing of the two during operation through theadjustable telescoping shaft 78, adjustable means are provided toconnect the two housings of these units. As will be seen from FIGS. 2and 13, the housing 25a of the cutting unit is provided with a pair oflaterally spaced, threaded blocks 110, and, similarly, the housing 24aof the forming unit is provided with two laterally spaced, threadedblocks 111. Extending between respective pairs of blocks are threadedshafts 112, and adjacent each of the forming unit blocks 111 theseshafts are provided with sprockets 113 over which a sprocket chain (notshown) is passed. Thus, the two threaded shafts 112 may be rotatedtogether in the same direction to maintain theselected spacingadjustment of the two units. Although not shown inthe drawing, asuitable hand wheel may be provided for rotating either one or the otherof these connecting shafts and simultaneously rotating the other. g

The formed articles 22a which are severed from the selvage after passingbetween the cutting roll 66 and backup roll 72 are ejected down a chuteand into stacking position in the stacking unit 26. The selvage fromwhich the articles have been severed is fed by threading fingers 96,upwardly between a stripping roll 97 and the periphery of the backuproll 72 and is conducted as seen in FIG. 1 to the granulating machine27.

To facilitate the feeding of the strip of formed articles into thecutting roll, a plate 99, associated with guide fingers 98, is providedover which the advancing strip passes. A roll 100 extends transverselyacross the plate 98 which is provided with an intermediate slot 101 toaccommodate the periphery of the roll 100. Beneath the roll 100'twowheels 102 are carried by a shaft 103 and driven by a chain 104. Thesewheels operate against the roll 100, which in turn is maintained underpressure against the wheels by cylinders 105 having piston rods 106which rotatably support the shaft of roller 100. The shaft 103 carryingthe wheels is driven by an air operated slip clutch, and torque controlis provided by varying the air pressure operating the slip clutchthrough a regulator. The surface speed of the wheels is designed to begreater than the surface speed of the cutter and backup rolls whichprovides a means for feeding the strip of formed articles by grippingthe selvage at each edge between the roller and wheels.

When the articles are discharged from between the cutting roll andbackup roll, air jets 107 (FIG. 13) may be employed to transfer thearticles down a chute 95. It has been found in practice that an air jetblown across the bottom edge of a flat article, such as a tray,decreases pressure on the underside of the tray and causes it to rapidlymake the transition from horizontal to vertical and descend down thechute into stacking position.

As previously stated, the forming and cutting units are mountedsymmetrically on rails and wheels so that they may be moved intoappropriate operating positions. The forming wheel and cutting deviceare linked together by the adjustable linkage system previouslydescribed, which permits proper cutting registration of the formedarticles in one dimension. Registration for the other dimension iscontrolled by the plate 98 and the guide fingers 99 thereon, thisassembly being movable from side to side by hand wheel 98a and adjustingshaft 98b, as seen in FIG. 12. The handle 98a turns the suitablythreaded shaft 98b which threadedly engages the plate assembly 98.

It should be pointed out that the surface speed of the cutting roll 66should be slightly faster than that of the forming wheel 24, thusproviding a uniform and constant tension at all times. Since the formingwheel is a polygon rather than a cylinder, the relationship of itsperimeter to the cutting roll must be taken into consideration. For

example, a mold or forming wheel with eight cavities and a cutting rollwith two cavities must be run on a four-toone ratio basis. Thisrelationship of revolutions must be exactly and precisely provided forby suitable gearing between the two machines. Nevertheless, the totalperimeter length of the forming wheel must be somewhat shorter than fourtimes the circumference of the cutting roll.

' edge and the periphery of the backup roll is borne by the peripheralengagement of the bearing rings 66a and the backup roll 72.

A preferred form of stacking unit is illustrated in FIGS. 16l8. The unitcomprises a base or support 115, the top wall of which carries a pair ofcentrally disposed, longi- Also, the thickness of the material must betaken into tudinally extending rails 116, supported for verticaladjustment by cross-bars 117 mounted on threaded rods 118 which extendthrough the top wall of the base and are adapted to be adjusted by athumb screw or the like 119. A suitable number of these rail supportsare provided in spaced relation along the top wall of the base tosupport the length of the rails 116.

On either side of the central rail assembly 116, the top wall of thebase carries a series of longitudinally spaced uprights 120 which aretransversely drilled to receive threaded rods 121, the opposite, innerends of which carry side rails 122. These side rails are adjustabletoward or away from one another by means of thumb screws 123. As will beseen from FIG. 13, the feeding end of the stacking unit 26 and its rails116, 122 is located immediately adjacent the lower end of the chute 95so as to receive the formed trays 22b which are presented to the railson edge. By adjusting the positions of the respective rails, any sizetrays can be accommodated.

A plunger 124, operated by a piston and cylinder device 125, pushes thestacked trays forwardly along the rails and, preferably, a suitablecounting device 126 automatically controls the number of trays to bepackaged.

At the opposite end of the rails just referred to, a bagging device,generally indicated at 127, is provided for completing the packagingoperation. This device comprises two laterally spaced vertical standards128 having vertical slots 129 for slidably receiving guide pins 130projecting from four supporting arms 131. Suitably secured to thesupporting arms and projecting forwardly therefrom are four, elongated,bag supporting members 132 which, as best seen in FIG. 18, are curved incrosssection to complement the profiles of the trays fed therebetween.These bag support members are properly spaced to fit within the open endof a plastic bag or the like 133 into which the trays are advanced fromthe rails 116 and 122.

In order to provide for the proper horizontal adjustment of the uprights128, their lower ends are secured to separate, relatively short angleirons 134 which are slidably secured to a long angle iron '135 by slotand pin arrangements 136. Thus, the bagging device may be adjustedlaterally by the slot and pin arrangements 136 and vertically by thesupporting arms 131 which are slidably supported in the vertical slots129.

From the foregoing, it is believed that the invention may be readilyunderstood by those skilled in the art without further description, itbeing borne in mind that numerous changes may be made in the detailsdisclosed without departing from the spirit of the invention as setforth in the following claims.

I claim:

1. An integrated system for continuously manufacturing three dimensionalarticles from an extruded sheet of foamed thermoplastic material,comprising the following elements in combination:

(a) a high speed extruder for extruding and expanding a continuous,fiat, relatively narrow sheet of foamed thermoplastic material;

(b) a rotatable forming wheel carrying a series of successive vacuummolds on its periphery, alinged with said extruder for successivelyengaging said sheet as it advances from said extruder, said formingwheel being in sufficiently close proximity to said extruder to utilizethe heat of extrusion in said sheet in forming said articles;

(c) means for rotating said wheel at a speed to accommodate saidadvancing sheet;

(d) a source of vacuum, valve means actuated by the rotation of saidwheel for successively evacuating the cavities of respective molds asthey are presented to said sheet and for maintaining a vacuum thereinfor a predetermined period of the rotation of said wheel;

(e) means for ejecting formed articles from successive molds; and

(f) a cutting roller coordinated with the rotation of said wheel and theactuation of said valve means, said cutting roller having on itsperiphery at least one cutting edge which conforms in contour to theedge boundary of said molded three dimensional articles, for severingformed articles from said sheet.

2. Apparatus as claimed in claim 1, wherein the periphery of saidforming wheel is provided with vacuum sealing means bordering thecavities of respective molds to insure the maintenance of contact of thesheet with said forming wheel.

3. Apparatus as claimed in claim 1, including means coordinating therotation of said cutting roller with the advance of said sheet from saidforming wheel to present the formed articles to the cutting rollerwithin the confines of said cutting edge.

4. Apparatus as claimed in claim 1, including means coordinating therotation of said forming wheel and cut- References Cited UNITED STATESPATENTS 1,750,708 3/ 1930 Edwards. 1,797,568 3/1931 Dean. 2,490,7 81 12/1949 Cloud. 3,162,077 12/ 1964 Briimmer.

WILLIAM J, STEPHENSON, Primary Examiner US. Cl. X.R.

